Drinking and Flying: Does Alcohol Consumption Affect the Flight and Echolocation Performance of Phyllostomid Bats?

In the wild, frugivorous and nectarivorous bats often eat fermenting fruits and nectar, and thus may consume levels of ethanol that could induce inebriation. To understand if consumption of ethanol by bats alters their access to food and general survival requires examination of behavioural responses to its ingestion, as well as assessment of interspecific variation in those responses. We predicted that bats fed ethanol would show impaired flight and echolocation behaviour compared to bats fed control sugar water, and that there would be behavioural differences among species. (Chiroptera, Phyllostomidae) sugar water (44 g of table sugar in 500 ml of water) or sugar water with ethanol before challenging them to fly through an obstacle course while we simultaneously recorded their echolocation calls. We used bat saliva, a non-invasive proxy, to measure blood ethanol concentrations ranging from 0 to >0.3% immediately before flight trials. Flight performance and echolocation behaviour were not significantly affected by consumption of ethanol, but species differed in their blood alcohol concentrations after consuming it.The bats we studied display a tolerance for ethanol that could have ramifications for the adaptive radiation of frugivorous and nectarivorous bats by allowing them to use ephemeral food resources over a wide span of time. By sampling across phyllostomid genera, we show that patterns of apparent ethanol tolerance in New World bats are broad, and thus may have been an important early step in the evolution of frugivory and nectarivory in these animals

Vision Impairs the Abilities of Bats to Avoid Colliding with Stationary Obstacles

Background: Free-flying insectivorous bats occasionally collide with stationary objects they should easily detect by echolocation and avoid. Collisions often occur with lighted objects, suggesting ambient light may deleteriously affect obstacle avoidance capabilities. We tested the hypothesis that free-flying bats may orient by vision when they collide with some obstacles. We additionally tested whether acoustic distractions, such as ‘‘distress calls’ ’ of other bats, contributed to probabilities of collision. Methodology/Principal Findings: To investigate the role of visual cues in the collisions of free-flying little brown bats (Myotis lucifugus) with stationary objects, we set up obstacles in an area of high bat traffic during swarming. We used combinations of light intensities and visually dissimilar obstacles to verify that bats orient by vision. In early August, bats collided more often in the light than the dark, and probabilities of collision varied with the visibility of obstacles. However, the probabilities of collisions altered in mid to late August, coincident with the start of behavioural, hormonal, and physiological changes occurring during swarming and mating. Distress calls did not distract bats and increase the incidence of collisions. Conclusions/Significance: Our findings indicate that visual cues are more important for free-flying bats than previously recognized, suggesting integration of multi-sensory modalities during orientation. Furthermore, our study highlight

A deep learning approach to photo–identification demonstrates high performance on two dozen cetacean species

We thank the countless individuals who collected and/or processed the nearly 85,000 images used in this study and those who assisted, particularly those who sorted these images from the millions that did not end up in the catalogues. Additionally, we thank the other Kaggle competitors who helped develop the ideas, models and data used here, particularly those who released their datasets to the public. The graduate assistantship for Philip T. Patton was funded by the NOAA Fisheries QUEST Fellowship. This paper represents HIMB and SOEST contribution numbers 1932 and 11679, respectively. The technical support and advanced computing resources from University of Hawaii Information Technology Services—Cyberinfrastructure, funded in part by the National Science Foundation CC* awards # 2201428 and # 2232862 are gratefully acknowledged. Every photo–identification image was collected under permits according to relevant national guidelines, regulation and legislation.Peer reviewedPublisher PD

Alpha shapes: Determining 3D shape complexity across morphologically diverse structures

Background. Following recent advances in bioimaging, high-resolution 3D models of biological structures are now generated rapidly and at low-cost. To utilise this data to address evolutionary and ecological questions, an array of tools has been developed to conduct 3D shape analysis and quantify topographic complexity. Here we focus particularly on shape techniques applied to irregular-shaped objects lacking clear homologous landmarks, and propose the new ‘alpha-shapes’ method for quantifying 3D shape complexity. Methods. We apply alpha-shapes to quantify shape complexity in the mammalian baculum as an example of a morphologically disparate structure. Micro- computed-tomography (μCT) scans of bacula were conducted. Bacula were binarised and converted into point clouds. Following application of a scaling factor to account for absolute differences in size, a suite of alpha-shapes was fitted to each specimen. An alpha shape is a formed from a subcomplex of the Delaunay triangulation of a given set of points, and ranges in refinement from a very coarse mesh (approximating convex hulls) to a very fine fit. ‘Optimal’ alpha was defined as the degree of refinement necessary in order for alpha-shape volume to equal CT voxel volume, and was taken as a metric of overall shape ‘complexity’. Results Our results show that alpha-shapes can be used to quantify interspecific variation in shape ‘complexity’ within biological structures of disparate geometry. The ‘stepped’ nature of alpha curves is informative with regards to the contribution of specific morphological features to overall shape ‘complexity’. Alpha-shapes agrees with other measures of topographic complexity (dissection index, Dirichlet normal energy) in identifying ursid bacula as having low shape complexity. However, alpha-shapes estimates mustelid bacula as possessing the highest topographic complexity, contrasting with other shape metrics. 3D fractal dimension is found to be an inappropriate metric of complexity when applied to bacula. Conclusions. The alpha-shapes methodology can be used to calculate ‘optimal’ alpha refinement as a proxy for shape ‘complexity’ without identifying landmarks. The implementation of alpha-shapes is straightforward, and is automated to process large datasets quickly. Beyond genital shape, we consider the alpha-shapes technique to hold considerable promise for new applications across evolutionary, ecological and palaeoecological disciplines

Tracking bottlenose dolphin movement and behavior in the Corpus Christi ship channel

Port Corpus Christi and Port Aransas, Texas, have undergone considerable infrastructure and oil exportation growth over the past 40 years. As humans continue to transform and exploit these coastal marine habitats, understanding dolphin and vessel interactions in the area is vital to improve conservation and management practices. As dolphins increased diving intervals and avoidance behavior in the presence of vessels, protecting marine mammals in areas of high vessel activity is urgent. To test the hypothesis that the movement patterns and behaviors of free-swimming bottlenose dolphins (Tursiops truncatus) are altered by vessel presence and size near Port Aransas, a shore-based digital theodolite is being used. Dolphin behavioral state and movement are analyzed in response to vessel activity. Distance between dolphin positions and habitat features are being calculated in ArcGIS Pro. Large vessels may elicit social and travel behavioral states as dolphins rode on the bows of most large tankers and cargo carriers. Dolphins mill and forage along channel banks and near the ferry crossing, suggesting that physical structures of concrete seawalls and mixing currents from vessel activity are utilized by dolphins to capture prey. In the morning and afternoon, dolphins oriented along the channel perimeter against the current flow with no positional changes in movement, indicating that tides may influence this population’s movement and behavior patterns. Understanding behavioral associations with diverse microhabitats in the Port Aransas area is crucial to conserve critical environments utilized by dolphins

Abundance of bottlenose dolphins (tursiops truncatus) in Texas coastal bend

Bottlenose dolphins (Tursiops truncatus) are the only species of marine mammal residing in the Texas Coastal Bend and have been specifically identified as imperiled by the National Oceanic and Atmospheric Administration. It has been almost 40 years since research has been published on the local population of bottlenose dolphins. In recent decades, the Texas Coastal Bend has substantially expanded in industrial growth and the Port of Corpus Christi is the third largest port in crude oil exportation in the U.S.A. The Corpus Christi Shipping Channel is also undergoing continual dredging to widen and deepen the channel to attract more commercial and industrial developments. With increasing and rapid changes and associated threats, it is important to monitor the local population of bottlenose dolphins and quantify how they are impacted by anthropogenic disturbance to inform policymakers for conservation mitigation. The population abundance of dolphins inhabiting the Texas Coastal Bend was determined by counting the number of animals based on unique markings. Photographs were captured of the individually distinctive dorsal fins of dolphins from a research vessel during 45 survey days since 2018. Photographs were subjected to quality control checks, cropped, matched by a minimum of two researchers, and scored based on quality. Preliminary results show that the current population of bottlenose dolphins consists of over 1,300 individuals, indicating a substantial population growth from the 593 dolphins reported in 1983. Findings from this study and additional photo- identification surveys will provide insights on the stability of the population that can be used as baseline data for conservation, including if dolphins are year-round residents and frequently inhabit areas of high vessel traffic

Utilization of computated tomography to view genital interactions in orcas (Orcinus orca) during intromission

Computed tomography (CT) has been an essential tool for imaging anatomy in a clinical setting. CT scans can provide insights on genital interactions between the sexes during intromission and is a valuable tool for species with internal fertilization as copulatory biomechanics can be discerned during penile penetration. We use CT scans of orcas (Orcinus orca) in simulated copulation to increase understanding of genital co- evolution and copulatory fit between the sexes. The penis of a postmortem sexually mature orca was inflated with pressurized saline to simulate erection and inserted in a ventral-ventral positioning into the vagina of a postmortem sexually mature female orca. The specimens were CT scanned in simulated copulation and resulting image slices were segmented by tissue type to create a 3D visualization of the genitalia interacting and determine significant landmarks in contact between the sexes. The ventral-ventral positioning produced a tight fit between the genitalia. One major vaginal fold was located cranially in the vagina. The integument of the penis maintaining contact throughout the vagina until tapering at the cervix, maintaining contact with the right distal wall of the vaginal tissue. Understanding of contact points between the sexes yields insights into possible stimulatory functions of genital contact in cetaceans (whales, dolphins, and porpoises) and sexual selection forces driving reproductive morphological co-evolution

Parameter estimates.

<p>d.f.  = 1.</p><p>Parameter estimates from the logistic regression model of all significant variables on the probability of bats colliding with obstacles. These parameter estimates show significance levels of the main effects (fabric and light), and interaction terms with date. The effects of transparent and dark treatments are included in the intercept term by SAS.</p

Probabilities of colliding as a function of fabric type and date.

<p>The probabilities of bats colliding with obstacles for each fabric type, with light levels fixed for (a) dark (n = 99 trials), (b) dim (n = 61 trials), and (c) bright (n = 66 trials) conditions. The arrow marks the cross-over point in the month where there is a change in the probability of colliding with obstacles.</p

Odds ratios.

<p>d.f.  = 1.</p><p>Odds ratios and significance levels of the main effects and interaction term contrasts on the probabilities of bats colliding with obstacles. Each contrast explains the likelihood of collision under one condition relative to a second condition. Main effects (fabric or light) odds ratios are fixed at the mean month date (derived considering the number of trials per night), while the interaction term (date) odds ratios show the effect of a 1 day increase in date on the main effects odds ratios.</p